The advantages of taut-line platforms are already well-known, in particular in the technical fields of drilling and of production in deep seas.
It is recalled that such floating platforms are anchored to the sea bottom by means of lines which are anchored to foundations and which operate under tension.
FIG. 1 shows an example of such a platform comprising a deck 1 and columns 2 which are anchored by lines 3 that are fixed via connectors 4 to a base 5.
One of the technical problems posed by the use of taut-line platforms is the problem of connecting the ends of the lines to the sea bottom.
There are several known solutions to this problem:
When the anchor depth of the sea bottom is not more than 150 meters, it is possible, although difficult, to guide the ends of the lines to the connectors by observing the connectors by means of a television camera, and then displacing the platform assembly as a function of the observations. To this end the platform is provided with tug means. In addition a cone is provided for guiding the end of the line.
Preferred implementations of the present invention enable the connection of the lines that are about a thousand meters long. However, the method can also be applied to lines of any length.
The above-mentioned technique is not suitable when there is a long distance between the platform and the ends of the lines, because of the lack of rigidity of long lines.
It is known how to position long flexible risers connecting a ship to an undersea station. A dynamically positionable ship is used for the purpose. This technique relies on the inertia of the ship being relative low in comparison to that of a platform weighing nearly 100,000 tons, and is therefore not directly applicable to a platform. In addition, platforms are not equipped with their own propulsion means.
Even if one line could be connected by this method, the operation could not be repeated for the other lines.
The lack of rigidity in the lines means that the techniques for positioning rigid-legged platforms are inapplicable.
An aim of the present invention is to define a method of prepositioning the connectors situated on the ends of the lines of a taut-line platform at such a distance from the receptacles for the connectors on the base, that connection can be performed quickly without any risk of bad aiming.